The present invention relates generally to an improved lens and, more particularly, to an improved lens which utilizes fluid, and particularly to fluid in the form of a hydrated hydrophilic polymer array, as its primary lens medium. The lens according to the present invention is especially suited for use as an intraocular lens.
It has long been recognized that ocular lenses made of glass or substantially rigid plastic result in irritation, discomfort and alteration of the normal corneal physiology. Therefore, attempts have been made to reduce these effects by using softer, more permeable lens materials, particularly in the area of contact lenses. For example, U.S. Pat. No. 2,241,415 to Moulton discloses an ophthalmic lens having a supporting portion formed of a thin, soft, pliable and slightly plastic material.
In recent years, so called "soft" contact lenses have been manufactured which utilize hydrogels as lens materials to reduce eye irritation and discomfort. For example, in U.S. Pat. No. 4,123,408, Gordon discloses a contact lens of a hydrogel composition wherein the hydrogel utilizes a polymerized water-insoluble, water-swellable polymer composition. U.S. Pat. No. 4,153,349 to Wichterle also discloses a method of making hydrogel contact lenses having improved lens properties. While "soft" contact lenses have reduced irritation and discomfort experienced while using prior art lenses, the soft contact lenses, while softer than prior art rigid lenses, must be sufficiently rigid to maintain the desired lens shape when utilized by the wearer and therefore a significant amount of foreign matter is introduced into the eye.
Any time foreign matter is introduced into the eye, there is a potential problem that irritation and discomfort will result even if the material is relatively soft. It will also hinder the passage of oxygen, nutrients, other gases and metabolites between cornea and tear film and thus potentially alter the normal physiology and clarity of the cornea. The ideal lens would utilize body fluids, such as lachrymal fluids, to form the desired lens and thereby completely eliminate the need for introduction of foreign material into the eye. However, since it is not possible to retain such fluid in a desired lens configuration, at least some type of structural member must be included to form the fluid into the shape of the lens.
Therefore, the use of fluid in connection with ocular devices has been generally relegated to purposes other than the formation of a primary lens medium. For example, U.S. Pat. No. 3,710,796 to Neefe discloses an ophthalmic dressing where a drug is impregnated into a transparent osmotic permeable material which serves to define the shape of the device. Diffusion of the drug out of its impregnated or dispersed state within this homogeneous polymer apparently determines the drug delivery rate. European Patent Application No. 32,517 published July 29, 1981 discloses a lens which permits the configuration of the device to a cornea by utilizing an insert filled with physiologically compatible fluid such as lachrymal fluid. However, the lens utilizes a soft contact material, not the fluid, as the primary lens medium.